gtpu_encap.c

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/*
 * Copyright (c) 2017 Intel and/or its affiliates.
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at:
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#include <vppinfra/error.h>
#include <vppinfra/hash.h>
#include <vnet/vnet.h>
#include <vnet/ip/ip.h>
#include <vnet/ethernet/ethernet.h>
#include <gtpu/gtpu.h>

/* Statistics (not all errors) */
#define foreach_gtpu_encap_error    \
_(ENCAPSULATED, "good packets encapsulated")

static char * gtpu_encap_error_strings[] = {
#define _(sym,string) string,
  foreach_gtpu_encap_error
#undef _
};

typedef enum {
#define _(sym,str) GTPU_ENCAP_ERROR_##sym,
    foreach_gtpu_encap_error
#undef _
    GTPU_ENCAP_N_ERROR,
} gtpu_encap_error_t;

#define foreach_gtpu_encap_next        \
_(DROP, "error-drop")                  \
_(IP4_LOOKUP, "ip4-lookup")             \
_(IP6_LOOKUP, "ip6-lookup")

typedef enum {
    GTPU_ENCAP_NEXT_DROP,
    GTPU_ENCAP_NEXT_IP4_LOOKUP,
    GTPU_ENCAP_NEXT_IP6_LOOKUP,
    GTPU_ENCAP_N_NEXT,
} gtpu_encap_next_t;

typedef struct {
  u32 tunnel_index;
  u32 teid;
} gtpu_encap_trace_t;

u8 * format_gtpu_encap_trace (u8 * s, va_list * args)
{
  CLIB_UNUSED (vlib_main_t * vm) = va_arg (*args, vlib_main_t *);
  CLIB_UNUSED (vlib_node_t * node) = va_arg (*args, vlib_node_t *);
  gtpu_encap_trace_t * t
      = va_arg (*args, gtpu_encap_trace_t *);

  s = format (s, "GTPU encap to gtpu_tunnel%d teid %d",
              t->tunnel_index, t->teid);
  return s;
}


#define foreach_fixed_header4_offset            \
    _(0) _(1) _(2) _(3)

#define foreach_fixed_header6_offset            \
    _(0) _(1) _(2) _(3) _(4) _(5) _(6)

always_inline uword
gtpu_encap_inline (vlib_main_t * vm,
                    vlib_node_runtime_t * node,
                    vlib_frame_t * from_frame,
                    u32 is_ip4)
{
  u32 n_left_from, next_index, * from, * to_next;
  gtpu_main_t * gtm = &gtpu_main;
  vnet_main_t * vnm = gtm->vnet_main;
  vnet_interface_main_t * im = &vnm->interface_main;
  u32 pkts_encapsulated = 0;
  u16 old_l0 = 0, old_l1 = 0, old_l2 = 0, old_l3 = 0;
  u32 thread_index = vlib_get_thread_index();
  u32 stats_sw_if_index, stats_n_packets, stats_n_bytes;
  u32 sw_if_index0 = 0, sw_if_index1 = 0, sw_if_index2 = 0, sw_if_index3 = 0;
  u32 next0 = 0, next1 = 0, next2 = 0, next3 = 0;
  vnet_hw_interface_t * hi0, * hi1, * hi2, * hi3;
  gtpu_tunnel_t * t0 = NULL, * t1 = NULL, * t2 = NULL, * t3 = NULL;

  from = vlib_frame_vector_args (from_frame);
  n_left_from = from_frame->n_vectors;

  next_index = node->cached_next_index;
  stats_sw_if_index = node->runtime_data[0];
  stats_n_packets = stats_n_bytes = 0;

  while (n_left_from > 0)
    {
      u32 n_left_to_next;

      vlib_get_next_frame (vm, node, next_index,
                           to_next, n_left_to_next);

      while (n_left_from >= 8 && n_left_to_next >= 4)
        {
          u32 bi0, bi1, bi2, bi3;
          vlib_buffer_t * b0, * b1, * b2, * b3;
          u32 flow_hash0, flow_hash1, flow_hash2, flow_hash3;
          u32 len0, len1, len2, len3;
          ip4_header_t * ip4_0, * ip4_1, * ip4_2, * ip4_3;
          ip6_header_t * ip6_0, * ip6_1, * ip6_2, * ip6_3;
          udp_header_t * udp0, * udp1, * udp2, * udp3;
          gtpu_header_t * gtpu0, * gtpu1, * gtpu2, * gtpu3;
          u64 * copy_src0, * copy_dst0;
          u64 * copy_src1, * copy_dst1;
          u64 * copy_src2, * copy_dst2;
          u64 * copy_src3, * copy_dst3;
          u32 * copy_src_last0, * copy_dst_last0;
          u32 * copy_src_last1, * copy_dst_last1;
          u32 * copy_src_last2, * copy_dst_last2;
          u32 * copy_src_last3, * copy_dst_last3;
          u16 new_l0, new_l1, new_l2, new_l3;
          ip_csum_t sum0, sum1, sum2, sum3;

          /* Prefetch next iteration. */
          {
            vlib_buffer_t * p4, * p5, * p6, * p7;

            p4 = vlib_get_buffer (vm, from[4]);
            p5 = vlib_get_buffer (vm, from[5]);
            p6 = vlib_get_buffer (vm, from[6]);
            p7 = vlib_get_buffer (vm, from[7]);

            vlib_prefetch_buffer_header (p4, LOAD);
            vlib_prefetch_buffer_header (p5, LOAD);
            vlib_prefetch_buffer_header (p6, LOAD);
            vlib_prefetch_buffer_header (p7, LOAD);

            CLIB_PREFETCH (p4->data, 2*CLIB_CACHE_LINE_BYTES, LOAD);
            CLIB_PREFETCH (p5->data, 2*CLIB_CACHE_LINE_BYTES, LOAD);
            CLIB_PREFETCH (p6->data, 2*CLIB_CACHE_LINE_BYTES, LOAD);
            CLIB_PREFETCH (p7->data, 2*CLIB_CACHE_LINE_BYTES, LOAD);
          }

          bi0 = from[0];
          bi1 = from[1];
          bi2 = from[2];
          bi3 = from[3];
          to_next[0] = bi0;
          to_next[1] = bi1;
          to_next[2] = bi2;
          to_next[3] = bi3;
          from += 4;
          to_next += 4;
          n_left_to_next -= 4;
          n_left_from -= 4;

          b0 = vlib_get_buffer (vm, bi0);
          b1 = vlib_get_buffer (vm, bi1);
          b2 = vlib_get_buffer (vm, bi2);
          b3 = vlib_get_buffer (vm, bi3);

          flow_hash0 = vnet_l2_compute_flow_hash (b0);
          flow_hash1 = vnet_l2_compute_flow_hash (b1);
          flow_hash2 = vnet_l2_compute_flow_hash (b2);
          flow_hash3 = vnet_l2_compute_flow_hash (b3);

          /* Get next node index and adj index from tunnel next_dpo */
          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_TX];
          sw_if_index1 = vnet_buffer(b1)->sw_if_index[VLIB_TX];
          sw_if_index2 = vnet_buffer(b2)->sw_if_index[VLIB_TX];
          sw_if_index3 = vnet_buffer(b3)->sw_if_index[VLIB_TX];
          hi0 = vnet_get_sup_hw_interface (vnm, sw_if_index0);
          hi1 = vnet_get_sup_hw_interface (vnm, sw_if_index1);
          hi2 = vnet_get_sup_hw_interface (vnm, sw_if_index2);
          hi3 = vnet_get_sup_hw_interface (vnm, sw_if_index3);
          t0 = &gtm->tunnels[hi0->dev_instance];
          t1 = &gtm->tunnels[hi1->dev_instance];
          t2 = &gtm->tunnels[hi2->dev_instance];
          t3 = &gtm->tunnels[hi3->dev_instance];

          /* Note: change to always set next0 if it may be set to drop */
          next0 = t0->next_dpo.dpoi_next_node;
          vnet_buffer(b0)->ip.adj_index[VLIB_TX] = t0->next_dpo.dpoi_index;
          next1 = t1->next_dpo.dpoi_next_node;
          vnet_buffer(b1)->ip.adj_index[VLIB_TX] = t1->next_dpo.dpoi_index;
          next2 = t2->next_dpo.dpoi_next_node;
          vnet_buffer(b2)->ip.adj_index[VLIB_TX] = t2->next_dpo.dpoi_index;
          next3 = t3->next_dpo.dpoi_next_node;
          vnet_buffer(b3)->ip.adj_index[VLIB_TX] = t3->next_dpo.dpoi_index;

          /* Apply the rewrite string. $$$$ vnet_rewrite? */
          vlib_buffer_advance (b0, -(word)_vec_len(t0->rewrite));
          vlib_buffer_advance (b1, -(word)_vec_len(t1->rewrite));
          vlib_buffer_advance (b2, -(word)_vec_len(t2->rewrite));
          vlib_buffer_advance (b3, -(word)_vec_len(t3->rewrite));

          if (is_ip4)
            {
              ip4_0 = vlib_buffer_get_current(b0);
              ip4_1 = vlib_buffer_get_current(b1);
              ip4_2 = vlib_buffer_get_current(b2);
              ip4_3 = vlib_buffer_get_current(b3);

              /* Copy the fixed header */
              copy_dst0 = (u64 *) ip4_0;
              copy_src0 = (u64 *) t0->rewrite;
              copy_dst1 = (u64 *) ip4_1;
              copy_src1 = (u64 *) t1->rewrite;
              copy_dst2 = (u64 *) ip4_2;
              copy_src2 = (u64 *) t2->rewrite;
              copy_dst3 = (u64 *) ip4_3;
              copy_src3 = (u64 *) t3->rewrite;

              /* Copy first 32 octets 8-bytes at a time */
#define _(offs) copy_dst0[offs] = copy_src0[offs];
              foreach_fixed_header4_offset;
#undef _
#define _(offs) copy_dst1[offs] = copy_src1[offs];
              foreach_fixed_header4_offset;
#undef _
#define _(offs) copy_dst2[offs] = copy_src2[offs];
              foreach_fixed_header4_offset;
#undef _
#define _(offs) copy_dst3[offs] = copy_src3[offs];
              foreach_fixed_header4_offset;
#undef _
              /* Last 4 octets. Hopefully gcc will be our friend */
              copy_dst_last0 = (u32 *)(&copy_dst0[4]);
              copy_src_last0 = (u32 *)(&copy_src0[4]);
              copy_dst_last0[0] = copy_src_last0[0];
              copy_dst_last1 = (u32 *)(&copy_dst1[4]);
              copy_src_last1 = (u32 *)(&copy_src1[4]);
              copy_dst_last1[0] = copy_src_last1[0];
              copy_dst_last2 = (u32 *)(&copy_dst2[4]);
              copy_src_last2 = (u32 *)(&copy_src2[4]);
              copy_dst_last2[0] = copy_src_last2[0];
              copy_dst_last3 = (u32 *)(&copy_dst3[4]);
              copy_src_last3 = (u32 *)(&copy_src3[4]);
              copy_dst_last3[0] = copy_src_last3[0];

              /* Fix the IP4 checksum and length */
              sum0 = ip4_0->checksum;
              new_l0 = /* old_l0 always 0, see the rewrite setup */
                clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b0));
              sum0 = ip_csum_update (sum0, old_l0, new_l0, ip4_header_t,
                                     length /* changed member */);
              ip4_0->checksum = ip_csum_fold (sum0);
              ip4_0->length = new_l0;
              sum1 = ip4_1->checksum;
              new_l1 = /* old_l1 always 0, see the rewrite setup */
                clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b1));
              sum1 = ip_csum_update (sum1, old_l1, new_l1, ip4_header_t,
                                     length /* changed member */);
              ip4_1->checksum = ip_csum_fold (sum1);
              ip4_1->length = new_l1;
              sum2 = ip4_2->checksum;
              new_l2 = /* old_l0 always 0, see the rewrite setup */
                clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b2));
              sum2 = ip_csum_update (sum2, old_l2, new_l2, ip4_header_t,
                                     length /* changed member */);
              ip4_2->checksum = ip_csum_fold (sum2);
              ip4_2->length = new_l2;
              sum3 = ip4_3->checksum;
              new_l3 = /* old_l1 always 0, see the rewrite setup */
                clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b3));
              sum3 = ip_csum_update (sum3, old_l3, new_l3, ip4_header_t,
                                     length /* changed member */);
              ip4_3->checksum = ip_csum_fold (sum3);
              ip4_3->length = new_l3;

              /* Fix UDP length and set source port */
              udp0 = (udp_header_t *)(ip4_0+1);
              new_l0 = clib_host_to_net_u16 (vlib_buffer_length_in_chain(vm, b0)
                                             - sizeof (*ip4_0));
              udp0->length = new_l0;
              udp0->src_port = flow_hash0;
              udp1 = (udp_header_t *)(ip4_1+1);
              new_l1 = clib_host_to_net_u16 (vlib_buffer_length_in_chain(vm, b1)
                                             - sizeof (*ip4_1));
              udp1->length = new_l1;
              udp1->src_port = flow_hash1;
              udp2 = (udp_header_t *)(ip4_2+1);
              new_l2 = clib_host_to_net_u16 (vlib_buffer_length_in_chain(vm, b2)
                                             - sizeof (*ip4_2));
              udp2->length = new_l2;
              udp2->src_port = flow_hash2;
              udp3 = (udp_header_t *)(ip4_3+1);
              new_l3 = clib_host_to_net_u16 (vlib_buffer_length_in_chain(vm, b3)
                                             - sizeof (*ip4_3));
              udp3->length = new_l3;
              udp3->src_port = flow_hash3;

              /* Fix GTPU length */
              gtpu0 = (gtpu_header_t *)(udp0+1);
              new_l0 = clib_host_to_net_u16 (vlib_buffer_length_in_chain(vm, b0)
                                             - sizeof (*ip4_0) - sizeof(*udp0)
                                             - GTPU_V1_HDR_LEN);
              gtpu0->length = new_l0;
              gtpu1 = (gtpu_header_t *)(udp1+1);
              new_l1 = clib_host_to_net_u16 (vlib_buffer_length_in_chain(vm, b1)
                                             - sizeof (*ip4_1) - sizeof(*udp1)
                                             - GTPU_V1_HDR_LEN);
              gtpu1->length = new_l1;
              gtpu2 = (gtpu_header_t *)(udp2+1);
              new_l2 = clib_host_to_net_u16 (vlib_buffer_length_in_chain(vm, b2)
                                             - sizeof (*ip4_2) - sizeof(*udp2)
                                             - GTPU_V1_HDR_LEN);
              gtpu2->length = new_l2;
              gtpu3 = (gtpu_header_t *)(udp3+1);
              new_l3 = clib_host_to_net_u16 (vlib_buffer_length_in_chain(vm, b3)
                                             - sizeof (*ip4_3) - sizeof(*udp3)
                                             - GTPU_V1_HDR_LEN);
              gtpu3->length = new_l3;
            }
          else /* ipv6 */
            {
              int bogus = 0;

              ip6_0 = vlib_buffer_get_current(b0);
              ip6_1 = vlib_buffer_get_current(b1);
              ip6_2 = vlib_buffer_get_current(b2);
              ip6_3 = vlib_buffer_get_current(b3);

              /* Copy the fixed header */
              copy_dst0 = (u64 *) ip6_0;
              copy_src0 = (u64 *) t0->rewrite;
              copy_dst1 = (u64 *) ip6_1;
              copy_src1 = (u64 *) t1->rewrite;
              copy_dst2 = (u64 *) ip6_2;
              copy_src2 = (u64 *) t2->rewrite;
              copy_dst3 = (u64 *) ip6_3;
              copy_src3 = (u64 *) t3->rewrite;
              /* Copy first 56 (ip6) octets 8-bytes at a time */
#define _(offs) copy_dst0[offs] = copy_src0[offs];
              foreach_fixed_header6_offset;
#undef _
#define _(offs) copy_dst1[offs] = copy_src1[offs];
              foreach_fixed_header6_offset;
#undef _
#define _(offs) copy_dst2[offs] = copy_src2[offs];
              foreach_fixed_header6_offset;
#undef _
#define _(offs) copy_dst3[offs] = copy_src3[offs];
              foreach_fixed_header6_offset;
#undef _
              /* Fix IP6 payload length */
              new_l0 =
                clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b0)
                                      - sizeof(*ip6_0));
              ip6_0->payload_length = new_l0;
              new_l1 =
                clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b1)
                                      - sizeof(*ip6_1));
              ip6_1->payload_length = new_l1;
              new_l2 =
                clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b2)
                                      - sizeof(*ip6_2));
              ip6_2->payload_length = new_l2;
              new_l3 =
                clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b3)
                                      - sizeof(*ip6_3));
              ip6_3->payload_length = new_l3;

              /* Fix UDP length  and set source port */
              udp0 = (udp_header_t *)(ip6_0+1);
              udp0->length = new_l0;
              udp0->src_port = flow_hash0;
              udp1 = (udp_header_t *)(ip6_1+1);
              udp1->length = new_l1;
              udp1->src_port = flow_hash1;
              udp2 = (udp_header_t *)(ip6_2+1);
              udp2->length = new_l2;
              udp2->src_port = flow_hash2;
              udp3 = (udp_header_t *)(ip6_3+1);
              udp3->length = new_l3;
              udp3->src_port = flow_hash3;

              /* IPv6 UDP checksum is mandatory */
              udp0->checksum = ip6_tcp_udp_icmp_compute_checksum(vm, b0,
                                                                 ip6_0, &bogus);
              if (udp0->checksum == 0)
                udp0->checksum = 0xffff;
              udp1->checksum = ip6_tcp_udp_icmp_compute_checksum(vm, b1,
                                                        ip6_1, &bogus);
              if (udp1->checksum == 0)
                udp1->checksum = 0xffff;
              udp2->checksum = ip6_tcp_udp_icmp_compute_checksum(vm, b2,
                                                                 ip6_2, &bogus);
              if (udp2->checksum == 0)
                udp2->checksum = 0xffff;
              udp3->checksum = ip6_tcp_udp_icmp_compute_checksum(vm, b3,
                                                        ip6_3, &bogus);
              if (udp3->checksum == 0)
                udp3->checksum = 0xffff;

              /* Fix GTPU length */
              gtpu0 = (gtpu_header_t *)(udp0+1);
              new_l0 = clib_host_to_net_u16 (vlib_buffer_length_in_chain(vm, b0)
                                             - sizeof (*ip6_0) - sizeof(*udp0)
                                             - GTPU_V1_HDR_LEN);
              gtpu0->length = new_l0;
              gtpu1 = (gtpu_header_t *)(udp1+1);
              new_l1 = clib_host_to_net_u16 (vlib_buffer_length_in_chain(vm, b1)
                                             - sizeof (*ip6_1) - sizeof(*udp1)
                                             - GTPU_V1_HDR_LEN);
              gtpu1->length = new_l1;
              gtpu2 = (gtpu_header_t *)(udp2+1);
              new_l2 = clib_host_to_net_u16 (vlib_buffer_length_in_chain(vm, b2)
                                             - sizeof (*ip6_2) - sizeof(*udp2)
                                             - GTPU_V1_HDR_LEN);
              gtpu2->length = new_l2;
              gtpu3 = (gtpu_header_t *)(udp3+1);
              new_l3 = clib_host_to_net_u16 (vlib_buffer_length_in_chain(vm, b3)
                                             - sizeof (*ip6_3) - sizeof(*udp3)
                                             - GTPU_V1_HDR_LEN);
              gtpu3->length = new_l3;
            }

          pkts_encapsulated += 4;
          len0 = vlib_buffer_length_in_chain (vm, b0);
          len1 = vlib_buffer_length_in_chain (vm, b1);
          len2 = vlib_buffer_length_in_chain (vm, b2);
          len3 = vlib_buffer_length_in_chain (vm, b3);
          stats_n_packets += 4;
          stats_n_bytes += len0 + len1 + len2 + len3;

          /* Batch stats increment on the same gtpu tunnel so counter is not
             incremented per packet. Note stats are still incremented for deleted
             and admin-down tunnel where packets are dropped. It is not worthwhile
             to check for this rare case and affect normal path performance. */
          if (PREDICT_FALSE ((sw_if_index0 != stats_sw_if_index) ||
                             (sw_if_index1 != stats_sw_if_index) ||
                             (sw_if_index2 != stats_sw_if_index) ||
                             (sw_if_index3 != stats_sw_if_index) ))
            {
              stats_n_packets -= 4;
              stats_n_bytes -= len0 + len1 + len2 + len3;
              if ( (sw_if_index0 == sw_if_index1 ) &&
                   (sw_if_index1 == sw_if_index2 ) &&
                   (sw_if_index2 == sw_if_index3 ) )
                {
                  if (stats_n_packets)
                    vlib_increment_combined_counter
                      (im->combined_sw_if_counters + VNET_INTERFACE_COUNTER_TX,
                       thread_index, stats_sw_if_index,
                       stats_n_packets, stats_n_bytes);
                  stats_sw_if_index = sw_if_index0;
                  stats_n_packets = 4;
                  stats_n_bytes = len0 + len1 + len2 + len3;
                }
              else
                {
                  vlib_increment_combined_counter
                      (im->combined_sw_if_counters + VNET_INTERFACE_COUNTER_TX,
                       thread_index, sw_if_index0, 1, len0);
                  vlib_increment_combined_counter
                      (im->combined_sw_if_counters + VNET_INTERFACE_COUNTER_TX,
                       thread_index, sw_if_index1, 1, len1);
                  vlib_increment_combined_counter
                      (im->combined_sw_if_counters + VNET_INTERFACE_COUNTER_TX,
                       thread_index, sw_if_index2, 1, len2);
                  vlib_increment_combined_counter
                      (im->combined_sw_if_counters + VNET_INTERFACE_COUNTER_TX,
                       thread_index, sw_if_index3, 1, len3);
                }
            }

          if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED))
            {
              gtpu_encap_trace_t *tr =
                vlib_add_trace (vm, node, b0, sizeof (*tr));
              tr->tunnel_index = t0 - gtm->tunnels;
              tr->teid = t0->teid;
           }

          if (PREDICT_FALSE(b1->flags & VLIB_BUFFER_IS_TRACED))
            {
              gtpu_encap_trace_t *tr =
                vlib_add_trace (vm, node, b1, sizeof (*tr));
              tr->tunnel_index = t1 - gtm->tunnels;
              tr->teid = t1->teid;
            }

          vlib_validate_buffer_enqueue_x4 (vm, node, next_index,
                                           to_next, n_left_to_next,
                                           bi0, bi1, bi2, bi3,
                                           next0, next1, next2, next3);
        }

      while (n_left_from > 0 && n_left_to_next > 0)
        {
          u32 bi0;
          vlib_buffer_t * b0;
          u32 flow_hash0;
          u32 len0;
          ip4_header_t * ip4_0;
          ip6_header_t * ip6_0;
          udp_header_t * udp0;
          gtpu_header_t * gtpu0;
          u64 * copy_src0, * copy_dst0;
          u32 * copy_src_last0, * copy_dst_last0;
          u16 new_l0;
          ip_csum_t sum0;

          bi0 = from[0];
          to_next[0] = bi0;
          from += 1;
          to_next += 1;
          n_left_from -= 1;
          n_left_to_next -= 1;

          b0 = vlib_get_buffer (vm, bi0);

          flow_hash0 = vnet_l2_compute_flow_hash(b0);

          /* Get next node index and adj index from tunnel next_dpo */
          sw_if_index0 = vnet_buffer(b0)->sw_if_index[VLIB_TX];
          hi0 = vnet_get_sup_hw_interface (vnm, sw_if_index0);
          t0 = &gtm->tunnels[hi0->dev_instance];
          /* Note: change to always set next0 if it may be set to drop */
          next0 = t0->next_dpo.dpoi_next_node;
          vnet_buffer(b0)->ip.adj_index[VLIB_TX] = t0->next_dpo.dpoi_index;

          /* Apply the rewrite string. $$$$ vnet_rewrite? */
          vlib_buffer_advance (b0, -(word)_vec_len(t0->rewrite));

          if (is_ip4)
            {
              ip4_0 = vlib_buffer_get_current(b0);

              /* Copy the fixed header */
              copy_dst0 = (u64 *) ip4_0;
              copy_src0 = (u64 *) t0->rewrite;
              /* Copy first 32 octets 8-bytes at a time */
#define _(offs) copy_dst0[offs] = copy_src0[offs];
              foreach_fixed_header4_offset;
#undef _
              /* Last 4 octets. Hopefully gcc will be our friend */
              copy_dst_last0 = (u32 *)(&copy_dst0[4]);
              copy_src_last0 = (u32 *)(&copy_src0[4]);
              copy_dst_last0[0] = copy_src_last0[0];

              /* Fix the IP4 checksum and length */
              sum0 = ip4_0->checksum;
              new_l0 = /* old_l0 always 0, see the rewrite setup */
                clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b0));
              sum0 = ip_csum_update (sum0, old_l0, new_l0, ip4_header_t,
                                     length /* changed member */);
              ip4_0->checksum = ip_csum_fold (sum0);
              ip4_0->length = new_l0;

              /* Fix UDP length and set source port */
              udp0 = (udp_header_t *)(ip4_0+1);
              new_l0 = clib_host_to_net_u16 (vlib_buffer_length_in_chain(vm, b0)
                                             - sizeof (*ip4_0));
              udp0->length = new_l0;
              udp0->src_port = flow_hash0;

              /* Fix GTPU length */
              gtpu0 = (gtpu_header_t *)(udp0+1);
              new_l0 = clib_host_to_net_u16 (vlib_buffer_length_in_chain(vm, b0)
                                             - sizeof (*ip4_0) - sizeof(*udp0)
                                             - GTPU_V1_HDR_LEN);
              gtpu0->length = new_l0;
            }

          else /* ip6 path */
            {
              int bogus = 0;

              ip6_0 = vlib_buffer_get_current(b0);
              /* Copy the fixed header */
              copy_dst0 = (u64 *) ip6_0;
              copy_src0 = (u64 *) t0->rewrite;
              /* Copy first 56 (ip6) octets 8-bytes at a time */
#define _(offs) copy_dst0[offs] = copy_src0[offs];
              foreach_fixed_header6_offset;
#undef _
              /* Fix IP6 payload length */
              new_l0 =
                clib_host_to_net_u16 (vlib_buffer_length_in_chain (vm, b0)
                                      - sizeof(*ip6_0));
              ip6_0->payload_length = new_l0;

              /* Fix UDP length  and set source port */
              udp0 = (udp_header_t *)(ip6_0+1);
              udp0->length = new_l0;
              udp0->src_port = flow_hash0;

              /* IPv6 UDP checksum is mandatory */
              udp0->checksum = ip6_tcp_udp_icmp_compute_checksum(vm, b0,
                                                                 ip6_0, &bogus);
              if (udp0->checksum == 0)
                udp0->checksum = 0xffff;

              /* Fix GTPU length */
              gtpu0 = (gtpu_header_t *)(udp0+1);
              new_l0 = clib_host_to_net_u16 (vlib_buffer_length_in_chain(vm, b0)
                                             - sizeof (*ip4_0) - sizeof(*udp0)
                                             - GTPU_V1_HDR_LEN);
              gtpu0->length = new_l0;
            }

          pkts_encapsulated ++;
          len0 = vlib_buffer_length_in_chain (vm, b0);
          stats_n_packets += 1;
          stats_n_bytes += len0;

          /* Batch stats increment on the same gtpu tunnel so counter is not
             incremented per packet. Note stats are still incremented for deleted
             and admin-down tunnel where packets are dropped. It is not worthwhile
             to check for this rare case and affect normal path performance. */
          if (PREDICT_FALSE (sw_if_index0 != stats_sw_if_index))
            {
              stats_n_packets -= 1;
              stats_n_bytes -= len0;
              if (stats_n_packets)
                vlib_increment_combined_counter
                  (im->combined_sw_if_counters + VNET_INTERFACE_COUNTER_TX,
                   thread_index, stats_sw_if_index,
                   stats_n_packets, stats_n_bytes);
              stats_n_packets = 1;
              stats_n_bytes = len0;
              stats_sw_if_index = sw_if_index0;
            }

          if (PREDICT_FALSE(b0->flags & VLIB_BUFFER_IS_TRACED))
            {
              gtpu_encap_trace_t *tr =
                vlib_add_trace (vm, node, b0, sizeof (*tr));
              tr->tunnel_index = t0 - gtm->tunnels;
              tr->teid = t0->teid;
            }
          vlib_validate_buffer_enqueue_x1 (vm, node, next_index,
                                           to_next, n_left_to_next,
                                           bi0, next0);
        }

      vlib_put_next_frame (vm, node, next_index, n_left_to_next);
    }

  /* Do we still need this now that tunnel tx stats is kept? */
  vlib_node_increment_counter (vm, node->node_index,
                               GTPU_ENCAP_ERROR_ENCAPSULATED,
                               pkts_encapsulated);

  /* Increment any remaining batch stats */
  if (stats_n_packets)
    {
      vlib_increment_combined_counter
        (im->combined_sw_if_counters + VNET_INTERFACE_COUNTER_TX,
         thread_index, stats_sw_if_index, stats_n_packets, stats_n_bytes);
      node->runtime_data[0] = stats_sw_if_index;
    }

  return from_frame->n_vectors;
}

static uword
gtpu4_encap (vlib_main_t * vm,
              vlib_node_runtime_t * node,
              vlib_frame_t * from_frame)
{
  return gtpu_encap_inline (vm, node, from_frame, /* is_ip4 */ 1);
}

static uword
gtpu6_encap (vlib_main_t * vm,
              vlib_node_runtime_t * node,
              vlib_frame_t * from_frame)
{
  return gtpu_encap_inline (vm, node, from_frame, /* is_ip4 */ 0);
}

VLIB_REGISTER_NODE (gtpu4_encap_node) = {
  .function = gtpu4_encap,
  .name = "gtpu4-encap",
  .vector_size = sizeof (u32),
  .format_trace = format_gtpu_encap_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN(gtpu_encap_error_strings),
  .error_strings = gtpu_encap_error_strings,
  .n_next_nodes = GTPU_ENCAP_N_NEXT,
  .next_nodes = {
#define _(s,n) [GTPU_ENCAP_NEXT_##s] = n,
    foreach_gtpu_encap_next
#undef _
  },
};

VLIB_NODE_FUNCTION_MULTIARCH (gtpu4_encap_node, gtpu4_encap)

VLIB_REGISTER_NODE (gtpu6_encap_node) = {
  .function = gtpu6_encap,
  .name = "gtpu6-encap",
  .vector_size = sizeof (u32),
  .format_trace = format_gtpu_encap_trace,
  .type = VLIB_NODE_TYPE_INTERNAL,
  .n_errors = ARRAY_LEN(gtpu_encap_error_strings),
  .error_strings = gtpu_encap_error_strings,
  .n_next_nodes = GTPU_ENCAP_N_NEXT,
  .next_nodes = {
#define _(s,n) [GTPU_ENCAP_NEXT_##s] = n,
    foreach_gtpu_encap_next
#undef _
  },
};

VLIB_NODE_FUNCTION_MULTIARCH (gtpu6_encap_node, gtpu6_encap)